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Thread: cpufreq policy stuck at 800 MHz

  1. #1
    Join Date
    Mar 2010
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    cpufreq policy stuck at 800 MHz

    This is to reopen very old thread 700865 because I am having the same annoying issue on Dell Latitude D830 with Karmic kernel 2.6.31-20-generic.

    If I disconnect AC for more then 16 seconds I need to stay disconnected to get full speed. Otherwise I get stuck to 800MHz. If I reconnect before 16 seconds full speed is kept.

    All states/governors/frequencies work ok unless I preform the described procedure. If I disable ACPI from grub params or bios it obviously does not happen. Suspend to disk/mem both work ok. I never noticed such an slow down on Windows before purging it. I recompiled kernel, changed acpi_cpufreq to module to reload it and replaced DSDT to no avail. Needless to say that standard
    /sys/devices/system/cpu?/* control files are present but useless to change cur_freq when locked down. This happens no matter what governor I have selected. I also upgraded from A12 to A15 bios.

    This is how to reproduce it :
    1. Boot on batery
    2. Wait 16 seconds
    3. Connect AC power


    OR

    • Boot on AC power
    • Remove AC Power
    • Wait 16 seconds
    • Reconnect AC Power


    Acpi events reflect just described procedure :
    Code:
    samuel@d830:~$ acpi_listen 
    #AC unplugged
    ac_adapter AC 00000080 00000000
    battery BAT0 00000080 00000001
    
    #AC plugged in
    ac_adapter AC 00000080 00000001
    #following events get me stuck to 800MHz
    processor CPU0 00000080 00000004
    processor CPU1 00000080 00000004
    battery BAT0 00000080 00000001
    battery BAT0 00000080 00000001
    
    #AC unplugged
    ac_adapter AC 00000080 00000000
    battery BAT0 00000080 00000001
    #16 seconds later (full speed recovered here but I am on BAT! argh!)
    processor CPU0 00000080 00000000
    processor CPU1 00000080 00000000
    This is my CPU info :
    Code:
    samuel@d830:~$ cat /proc/cpuinfo 
    processor	: 0
    vendor_id	: GenuineIntel
    cpu family	: 6
    model		: 15
    model name	: Intel(R) Core(TM)2 Duo CPU     T7250  @ 2.00GHz
    stepping	: 13
    cpu MHz		: 2000.000
    cache size	: 2048 KB
    physical id	: 0
    siblings	: 2
    core id		: 0
    cpu cores	: 2
    apicid		: 0
    initial apicid	: 0
    fdiv_bug	: no
    hlt_bug		: no
    f00f_bug	: no
    coma_bug	: no
    fpu		: yes
    fpu_exception	: yes
    cpuid level	: 10
    wp		: yes
    flags		: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm tpr_shadow vnmi flexpriority
    bogomips	: 3989.21
    clflush size	: 64
    power management:
    
    processor	: 1
    vendor_id	: GenuineIntel
    cpu family	: 6
    model		: 15
    model name	: Intel(R) Core(TM)2 Duo CPU     T7250  @ 2.00GHz
    stepping	: 13
    cpu MHz		: 2000.000
    cache size	: 2048 KB
    physical id	: 0
    siblings	: 2
    core id		: 1
    cpu cores	: 2
    apicid		: 1
    initial apicid	: 1
    fdiv_bug	: no
    hlt_bug		: no
    f00f_bug	: no
    coma_bug	: no
    fpu		: yes
    fpu_exception	: yes
    cpuid level	: 10
    wp		: yes
    flags		: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm tpr_shadow vnmi flexpriority
    bogomips	: 3989.97
    clflush size	: 64
    power management:
    I also get an strange kernel log when AC is plugged in
    Code:
    Mar 24 19:53:32 d830 kernel: [  870.421651] atkbd.c: Unknown key pressed (translated set 2, code 0x8d on isa0060/serio0).
    Mar 24 19:53:32 d830 kernel: [  870.421657] atkbd.c: Use 'setkeycodes e00d <keycode>' to make it known.
    This is what I get when locked to 800Mhz
    Code:
    root@d830:~# cpufreq-info 
    cpufrequtils 005: cpufreq-info (C) Dominik Brodowski 2004-2006
    Report errors and bugs to cpufreq@vger.kernel.org, please.
    analyzing CPU 0:
      driver: acpi-cpufreq
      CPUs which need to switch frequency at the same time: 0
      hardware limits: 800 MHz - 2.00 GHz
      available frequency steps: 2.00 GHz, 1.60 GHz, 1.20 GHz, 800 MHz
      available cpufreq governors: conservative, ondemand, userspace, powersave, performance
      current policy: frequency should be within 800 MHz and 800 MHz.
                      The governor "userspace" may decide which speed to use
                      within this range.
      current CPU frequency is 800 MHz (asserted by call to hardware).
    analyzing CPU 1:
      driver: acpi-cpufreq
      CPUs which need to switch frequency at the same time: 1
      hardware limits: 800 MHz - 2.00 GHz
      available frequency steps: 2.00 GHz, 1.60 GHz, 1.20 GHz, 800 MHz
      available cpufreq governors: conservative, ondemand, userspace, powersave, performance
      current policy: frequency should be within 800 MHz and 800 MHz.
                      The governor "performance" may decide which speed to use
                      within this range.
      current CPU frequency is 800 MHz (asserted by call to hardware).
    Similar posts :
    http://ubuntuforums.org/showthread.php?t=700865
    http://bbs.archlinux.org/viewtopic.php?id=42208
    https://bugzilla.redhat.com/show_bug.cgi?id=511840
    http://swiss.ubuntuforums.org/showthread.php?t=1069429
    http://www.archivum.info/ubuntu-bugs...Pad-T60p).html
    http://www.mail-archive.com/ubuntu-b...sg1858658.html
    https://bugs.launchpad.net/ubuntu/+s...22/+bug/132271
    Last edited by samuelventura; March 25th, 2010 at 06:33 AM.

  2. #2
    Join Date
    Mar 2010
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    2

    Re: cpufreq policy stuck at 800 MHz

    It turns out that using a 90W power adapter MOSTLY solves this issue. Bios seems to perform a current stress or some other magic to find out adapter power rating. Whatever it does to detect rating it discriminates under-rated adapters and imposes the 800Mhz penalty.

    Now, with the right adapter it still locks to 800MHz on AC disconnect and takes 16 seconds get back to full speed. We are closer to an acceptable solutions but still annoyed. Why would some one consider a better alternative to get full speed on battery but not when connected to a under-rater adapter?
    Last edited by samuelventura; March 25th, 2010 at 06:51 PM.

  3. #3
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    Re: cpufreq policy stuck at 800 MHz

    It seems I'm having the same problem.
    But my case it happens without unplugging the adapter.
    (I'm using Dell E6400)

    The symptoms are the same, and for me it seems it happens when I have heavy Python computation routine going on, or a lot of flash playing, or HD movie playing. It happens a lot when I play 720 HD movies.

    It is really annoying ..
    Oh by the way, I'm using openSUSE 11.2 64bit.

  4. #4
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    Re: cpufreq policy stuck at 800 MHz

    I had pretty much the same problem, and in my case, the problem was clogged vent of my laptop. I just cleaned it and it was pretty clogged by dust. So when CPU load was high the temperature got too high the computer reduced the CPU frequency.

    I'm not sure if your problem is because of this, but I think it is worth checking out.

    -Joon

  5. #5
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    Ubuntu 12.04 Precise Pangolin

    Re: cpufreq policy stuck at 800 MHz

    I'm having the exact same issue, and it's driving me crazy. I can't watch any type of video anymore because the CPU scales down and the video becomes unwatchable.

    Anyone figure out a solution yet?

  6. #6
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    Re: cpufreq policy stuck at 800 MHz

    Quote Originally Posted by Ingenium View Post
    I'm having the exact same issue, and it's driving me crazy. I can't watch any type of video anymore because the CPU scales down and the video becomes unwatchable.

    Anyone figure out a solution yet?
    As I said, if you haven't cleaned your vent for a long time, it might be a good idea to open up your machine and get rid of dust. In my case it solved the problem. I guess it is likely to be more severe in laptops.

    What happens is since the vent is clogged, CPU temperature gets too high and the computer automatically turn the clock down.

  7. #7
    Join Date
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    Re: cpufreq policy stuck at 800 MHz

    Thanks for the suggestion, but I think mine is caused by someting else. The laptop is only 8 months old and is always kept on a clean desk (not set on carpet or anything). I actually opened up the system 4 days ago, and the fan and vent were both completely clear. I was surprised that nothing had built up. Under load at 2.8GHz, the CPU climbs and stabilizes at 62-64C (bounces up and down between the two) for 5-10 seconds before it gets throttled down to 800MHz. That seems like a pretty normal temperature under high load.



    Quote Originally Posted by joonR View Post
    As I said, if you haven't cleaned your vent for a long time, it might be a good idea to open up your machine and get rid of dust. In my case it solved the problem. I guess it is likely to be more severe in laptops.

    What happens is since the vent is clogged, CPU temperature gets too high and the computer automatically turn the clock down.

  8. #8
    Join Date
    May 2008
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    Re: cpufreq policy stuck at 800 MHz

    http://techmonks.net/bypassing-the-d...adapter-issue/

    I solve the problem as this post! The guy is really human being!
    Bill Z
    stat -c %a filename

  9. #9
    Join Date
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    Ubuntu 14.04 Trusty Tahr

    Re: cpufreq policy stuck at 800 MHz

    Hi, this is an old thread so it has been closed, please do not post in threads that are a year or more old, and thanks for sharing.

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